The present invention relates to electromagnetic separation methods and, more particularly, to a method of separating a superconducting powder from a mixture with other powders.
The advent of high temperature ceramic superconductors has raised the prospect of using liquid nitrogen rather than liquid helium as a coolant for superconducting devices. One problem with these high temperature superconductors is that, as conventionally synthesized, they consist of mixtures of different phases having different superconductivity transition temperatures. Some of these phases are in fact not superconductive at all.
It has been proposed to separate powdered mixtures of ceramic superconductors into superconducting and nonsuperconducting fractions by moving the powder through a static, permanent magnetic field. By the Meissner effect, the magnetic field repels the superconducting fraction. Representative patents disclosing such methods include U.S. Pat. No. 4,828,685, to Stephens, U.S. Pat. No. 5,049,540, to Park et al., and U.S. Pat. No. 5,268,353, to Ohara et al.